Don't panic! There is a chance you may recover it from your domain's config.xml.

Administrator's password is encrypted using one-way SHA algorithm, and cannot be
decrypted without enormous computational power. Luckily, when a domain is created,
the nodemanager's default password is made equal to administrator's one.
Nodemanager's password is encrypted with 3DES or AES, and can be decrypted.

Recover passwords for your domain

Upload the security/SerializedSystemIni.dat file from your domain along with config/config.xml.
All passwords in config.xml file will be decrypted and shown to you in clear text.
Nodemanager's password is likely matches your administrator's password (unless it was changed later).

You may also decrypt passwords for JDBC datasources, JMS bridge endpoints or in boot.properties file.

Security Note

No decrypted passwords are saved anywhere on this server! They are erased from memory the moment you get them.

Why I built this service?

My team has more than 20 domains in use, and forgotten passwords problem often infuriates me.
First I wrote a simple command-line utility to do the recovery, and later, seeing a large number
of requests online, made it a public service.

FAQ

Is It A Security Breach?

No, it is not.

Serialized System Ini file should only be accessible by the legitimate Weblogic domain administrators.

Regular users or hackers shall not be able to read it, and so cannot use this service to break into someone's system.

What WLS versions are supported?

It's tested with WLS 9.2, WLS 10 and WLS 11.

Earlier versions (7.x, 8.x) should work too. Later versions may not work.